As reported on bungie.net, the Myth II b.net server has gone down due to a DNS failure (read: not Bungie's fault). While bad in the short term, the good news is that the online crew that cares about YOU - THE GAMER, will ressurect the Myth:TFL server as well once they get the hardware set up in Redmond:
So, once everything is up and running, it will simply be a matter of DNS propagation before you can get back online. As some of you may remember from our initial move West, this process can take anywhere from a day to a month, or longer, depending on your ISP, routers, etc. This time, however, you won't have to download a new patch, and hopefully everyone will be able to get to Bungie.net soon.
Happy days are... well, they will be here again sometime Soon(tm). Thanks Mordia and Tommy G.